Supported olefin polymerization catalyst, its preparation and use

ABSTRACT

Olefin polymerization comprising catalysts based on a metallocene, an alumoxane and a support are disclosed. The process for the preparation of a supported olefin ploymerization catalyst comprises:a) a metallocene/activator reaction product, a solvent capable of dissolving it, and a porous support are brought into mutual contact, andb) the solvent is removed,and wherein step a) is carried out so that the porous support is impregnated with a volume of the metallocene/activator reaction product and solvent, which does not exceed the total pore volume of the support.

The invention relates to a new process for the preparation of asupported olefin polymerization catalyst. The invention also relates toa supported olefin polymerization catalyst prepared by such a processand its use for the homo- and copolymerization of olefins as well as anovel process for the preparation of polyethylene having a high bulkdensity.

Alpha-olefins, including ethylene, have so far been polymerized (homo-or copolymerized) by using heterogenous catalyst systems made up of aprocatalyst based on a transition metal and a cocatalyst based onaluminum alkyl. It has been observed that the homogenous or supportedcatalyst systems, the pro-catalyst component of which is based onmetallocene compounds such as bis (cyclopentadienyl) titanium dialkyl orbis (cyclopentadienyl) zirconium alkoxy, or chlorides of these,alumoxane or an ionic activator having been used as their activator, arealso useful in the polymerization of ethylene.

A generally known problem in the use of metallocene catalysts is thepoor morphology of the forming polymer material; this is seen inparticular in a low bulk density and in the polymer beingnon-homogenous. Since the so-called replica phenomenon applies topolymerization, i.e. the forming polymer particles obtain a morphologysimilar to that of the catalyst particles used for their preparation,the problem can be solved only by improving the morphology of thecatalyst used for the polymerization.

DE patent publication 2 608 863 discloses the use, for ethylenepolymerization, of a catalyst system made up ofbis-(cyclopentadienyl)titanium dialkyl, aluminum trlalkyl, and water. DEpatent publication 2 608 933 describes an ethylene polymerizationcatalyst system made up of zirconcenes having the general formula(Cp)_(n)ZrY_(4−n), where Cp is a cyclopentadienyl, n is a numeral 1-4, Yis group R, CH₂AlR₂, CH₂CH₂AlR₂ or CH₂CH(AlR₂)₂, R being an alkyl groupor a metal alkyl group; of an aluminum trialkyl cocatalyst; and ofwater.

European patent application 35242 discloses a method for the preparationof ethylene polymers and atactic propylene polymers in the presence of ahalogen-free Ziegler-Natta catalyst system made up of (1) acyclopentadienyl compound having the formula (Cp)_(n)MY_(4−n), where Cpand n are the same as above, M is a transition metal, preferablyzirconium, and Y is a hydrogen atom, a C₁-C₅ alkyl group or metal alkylgroup or a radical having the general formula CH₂AlR₂, CH₂CH₂AlR₂ orCH₂CH(AlR₂)₂, where R is a C₁-C₅ alkyl group or metal alkyl group; andof (2) alumoxane serving as an activator.

Homogenous catalyst systems in which a metallocene or alumo-xane is usedhave been disclosed, for example, in EP patent application 69951 andU.S. Pat. No. 4,404,344. It has been known in the art to support themetallocene catalyst on a carrier. DE 3240382C2 teaches a catalyst,which comprises alumoxane and a cyclopentadienyl titanium or zirconiumcompound supported on a dried inorganic filler, which can be anyinorganic compound, also silicate, quartz and aluminium-oxid. However,excess amounts of solvents are used and the inventors strive to getfiller into the polymer. Use of supports for metallocene catalysts isalso disclosed in EP 0037894B1.

Application publication 862625 discloses a method for the preparation ofa supported catalyst intended for olelefin polymerization, whereinalumoxane in an inert hydrocarbon solvent and a metallocene of a 4A, 5Aor 6A metal of the Periodic Table are added to a slurry of the supportin an inert hydro-carbon solution.

EP patent publication 279863 describes the preparation, by a slurryprocess, of a catalyst intended for the polymerization of alpha-olefins.The catalyst thereby obtained is further given a finishing treatment bypolymerizing olefin onto its surface; this suggests a poor morphology ofthe original catalyst, an attempt being made to improve it by thisso-called prepolymerization.

Publication U.S. Pat. No. 5,017,665 discloses a catalyst suitable forthe copolymerization of ethylene and 1,4-hexadiene, the catalyst beingprepared by adding 330 ml of a 10% alumoxane solution in toluene to 800g of silica powder (Davison 948). Thereafter, 250 ml of toluene isfurther added to the silica treated with alumoxane, whereafter 2.5 g ofbis(indenyl) zirconium dichloride slurried in 40 ml of toluene is addedto the obtained slurry. Finally the treated support is dried. Table I ofthe said patent publication shows that the activity of the obtainedcatalyst is not very good; with a catalyst feed rate of 1 g of catalystper hour, only approx. 100 g of polyethylene per hour is obtained, whichis a very low activity for practical purposes.

Publications EP-347129 and U.S. Pat. No. 5,001,205 disclose a processfor the preparation of a bis (cyclopentadienyl) zirconium alumoxanecatalyst on a silica support, wherein 30 ml of a methyl alumoxanesolution in toluene was poured onto 15 g of silica gel and was dried.Thereafter a solution of bis (cyclopentadienyl) zirconium dichloridederivative in toluene was added in drops to 2 g of the saidalumoxane-treated silica gel, and a small amount of toluene was furtheradded to form a slurry. Finally the slurry was dried, and a supportedcatalyst havina a zir-conium concentration of approx. 0.5% by weight wasobtained. Before the actual polymerization, the catalyst was coated byprepolymerization. Thus, the catalysts of these publications are alsoprepolymerized, which suggests a poor morphology of the originalcatalyst, an attempt being made to improve it by prepolymerization.

Patent CA-1268753 describes the bonding of a metallocene to a support,but in this publication a reaction product of a metallocene andalumoxane on the support is not formed; the alumoxane serves as aconventional cocatalyst,

Publication U.S. Pat. No. 5,240,894 discloses a process for thepreparation of a supported metallocent/alumoxane catalyst system,wherein first a metallocene/alumoxane reaction solution is formed, aporous support is added to the solution, the solvent is removed byevaporation, and the formed catalyst precursor is possibly subjected toprepolymerization, Although this publication proposes the mixing of thesupport with a completed metallocene/alumoxane reaction product, theneed for prepolymerization suggests deficient morphology of thecatalyst. The process described in this U.S. publication ischaracterized in that the solvent is used in excess relative to the porevolume of the support. In this case the adsorption of the catalystcomponents requires an affective evaporation step, in which case theabove-mentioned components, when precipitating, tend to be accumulate onthe surface of the support rather than to be adsorbed evenly inside thepores. this slurry method is typical of the prior art.

The methods generally used in the prior-art patent literature for thepreparation of supported metallocene-alumoxane catalysts are mostcommonly so-called slurry processes, in which an inert support isslurried in an inert hydrocarbon such as pentane, heptane or toluene.The catalyst components metallocene and alumoxane are then added to thisslurry. In some cases the support is treated separately with a solutionof the metallocene and separately with a solution of the alumoxane.Thereafter the inert hydrocarbon is evaporated by using a hightemperature and/or vacuum. The product obtained is a catalyst in whichthe active components are attached to a sopport. Judging from the above,there have always been the problems of poor morphology of the catalyst,an uneven distribution of the substances on the support, and thus also apoor quality of the polymer particles and a low catalyst activity.

The object of the present invention is to provide a supported olefinpolymerization catalyst having as good an activity as possible. Theinvention also aims at as good a catalyst morphology as possible, inturn giving aood morphology to the forming olefin polymer. The aim isadditionally to provide a supported olefin polymerization catalyst inwhich the active components of the catalyst are evenly distributed overthe support particles. In particular, the invention aims at producing asupported olefin polymerization catalyst which has the above-mentionedgood properties and is based on a transition-metal metallocene, anactivator, and a porous support. Furthermore, the process for thepreparation of an olefine polymerization catalyst must be simple,efficient, and economical.

SUMMARY OF THE INVENTION

The above objects have now been accomplished with a new process for thepreparation of a suported olefin polymerization catalyst. It has thusbeen realized that a supported olefin polymerization catalyst moreactive and of a better quality than previously can be obtained by aprocess which comorises steos of

(1) providing a porous support, comprising an inorganic oxide of anelement chosen from groups 2(A), 3(B) and 4 of the Periodic Table(Hubbard),

(2) providing a solution comprising

(2.1) the reaction product of

(2.1.1) a metallocene of the formula (I)

(CP)_(m)R_(n)MR′_(o)X_(p)  (I)

 wherein Cp is an unsubstituted or substituted and/or fused homo- orheterocyclopentadienyl, R is a group of 1-4 atoms connecting two Cprings, M is a transition metal of group 4A, 5A or 6A, R′ is ahydrocarbyl or hydrocarboxyl group having 1-20 carbon atoms, and X is ahalogen atom, and wherein m=1-3, n=0 or 1, o=0-3, p=0-3, and the summ+n+p=the same as the state of oxidation state of M, and

(2.1.2) an alumoxane of the formula (II)

R″—(AlO)_(x)—AlR″₂  (II)

 which formula (II) depicts a linear compound, and/or of the formula(III)

 which formula (III) depicts a cyclic compound, and in which formulae(II and III) x is 1-40, y is 3-40, and R″ is an alkyl group having 1-20carbon atoms, and

(2.2) a solvent, capable of dissolving the reaction product,

(3) impregnating the porous support with a volume of the solution, whichdoes not exceed the total pore volume of the porous support, and

(4) recovering the impregnated porous support, the pores of which arefilled with said solution.

The invention is thus based on the realization that the prior technologydescribed above incorporates a mistake, namely the adding of themetallocene and the alumoxane to the support separately and to a slurryof the support, or the immersing of the support in ametallocene/activator reaction product. In prior-known patentliterature, a solution of a metallocene/alumoxane reaction product isprepared and the support is immersed in it whereafter the solvent isevaporated. In the process now developed, the metallocene and theactivator are first allowed to react with each other to form a reactionproduct. This reaction is seen, among other things, as a change of colorof the reaction mixture. Thereafter the porous support is impregnatedwith an amount at maximum its pore volume with the said reaction productand solvent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bar graph analysis of the polymer particle size distributionof Example 7.

FIG. 2 is a graph of the molecular weight of the polymer vs. particlediameter of Example 7.

FIG. 3 is a graph of the polydispersity vs. particle diameter of Example7.

FIG. 4 is a bar graph analysis of the polymer particle size distributionof Example 8.

FIG. 5 is a graph of the molecular weight of the polymer vs. particlediameter of Example 8.

FIG. 6 is a graph of the polydispersity vs. particle diameter of Example8.

FIG. 7 is a bar graph of the polymer particle size distribution ofExample 9.

FIG. 8 is a bar graph of the polymer particle size distribution ofExample 9.

FIG. 9 is a bar graph of the polymer particle size distribution ofExample 9.

The good results of the process according to the invention may be due toa number of phenomena. One explanation may be that the adding of theactive components of th catalyst either to a slurry of catalystparticles and/or separately as a solution to contact with the catalystparticls has the consequence that the components will be unable eitherto diffuse into the capillary pores of the catalyst particles or toreact mutually in them. Another problem may be that the active catalystcompnents tend to prcipitate on the surface of the support particleswhen the medium has been evaporated sufficiently, in which case all theactive material will not have time to travel to the interior of thesupport particles. This is possible, for example, when the support isimmersed in a reaction product solution. A third problem is that thesolubility of the metallocene in a hydrocarbon solvent is so low that,being in solid form, it will not come into contact with the pore surfaceof the support and thus cannot form with alumoxane a layer evenlycovering the support. Regardless of the phenomenon underlying thepresent invention, the essential idea is that first a reaction productof the metallocene and the alumoxane, is produced, and a solid supportis impregnated with the reaction product together with a solvent so thatthe pore spaces of the support are just barely filled.

What is involved is an impregnation which does not lead to substantialagglomeration of the support, i.e. the support will be a powder with adry-feeling texture even after the treatment.

Another advantage of the invention is its extremely simple and rapidpreparation process. Since the solvent is not used in excess, this makesunnecessary the evaporation treatment of large amounts of solvent, withrecoveries and recycling, steps which especially in industrialproduction substantially increase both the time and cost of catalystpreparation.

According to a preferred embodiment of the invention, in theabove-mentioned step (3) the solution is used in such an amount inproportion to the support that substantially all of the pore volume isfilled with the reaction product and solution. This pore fillingutilizes maximally the physical properties of the support pores. In porefilling, a solution of the reaction product of a metallocene and analumoxane is added in a volume corresponding to the pore volume of thesupport onto the inert support. Thereby, the pores in the support arefilled and the structure of the catalyst will be very homogenousthroughout the catalyst plarticle.

The contacting in step (3) may occur, for example, so that the porevolume of the porous support is totally impregnated with the solvent,whereafter the support is contacted with a metallocene/alumoxanereaction product, which, when coming into contact with the solvent inthe pores, diffuses into the pores. It is, however, advantageous if instep (3):

(3.1) a solution is produced which comprises the said reaction productand a solvent, and

(3.2) the porous support is impregnated with the solution.

The advantage of the process according to the present invention can beseen clearly in a comparison of catalysts prepared in different ways.The morphology of a catalyst prepared by a conventional slurry processis very poor. This can be seen in the disadvantageous shape of theobtained catalyst particles and in an uneven distribution of the activecomponents. From this it follows that the morphology of the polymerparticles is also poor (so-called replica phenomenon), the bulk density(ED) of the plastics material in the reactor is low, the particle sizedistribution is wide, and different particles have different plasticqualities (differences mainly in molecular weight and in molecularweight distribution).

It is advantageous for the process according to the present invention ifthe metallocene/alumoxane reaction product and the solution are used insuch amounts that the transition-concentration in the support,calculated as zirconium, will be approx. 0.2-2.0% by weight, preferablyapprox. 0.6-1.6% by weight. In the process according to the invention itis also advantageous if the molar ratio of the alumoxane to themetallocene, calculated as the ratio of the aluminum of an alumoxaneactivator to the transition metal, is within the range 100:1-1:1,preferably 80:1-20:1 and most preferably 50:1-25:1.

In the invention, a supported olefin polymerization catalyst is preparedby using at least one metallocene compound. By metallocene is meant ametallic derivative of cyclopentadiene, and in particular a metallicderivative to which a cyclopentadienyl group is bonded with a π bond.The metallocenes used in the invention contain at least one suchcyclopentadienyl ring. The metal of the metallocene is a transitionmetal of any of groups 4A, 5A and 6A of the Periodic Table (Hubbard),preferably of group 4A or 5A (Hubbard), such as titanium, zirconium,hafnium, chromium, or vanadium. Titanium and zirconium are especiallypreferable metals. The cyclopentadienyl ring may be unsubstituted or maycontain substituents, such as hydrocarbyls. The cyclopentadienyl ringmay also be fused, for example, with an aromatic or cycloalkyl ring. Onthe other hand, the ring atom of the cyclopentadienyl ring may also be aheteroatom. The metallocene used in the invention may contain one, twoor three cyclopentadienyl rings, but preferably two rings.

According to the invention, the metallocene is a compound according toFormula (I)

(Cp)_(m)R_(n)MR′_(o)X_(p)  (I)

where Cp is an unsubstituted or substituted and/or fused homo- orheterocyclopentadienyl, R is a group of 1-4 atoms connecting 2 Cp rings,M is a transition metal of group 4A, 5A or 6A (Hubbard), R′ is ahydrocarbyl or hydrocarboxy group having 1-2 carbon atoms, and X is ahalogen atom, in which case m=1-3, n=0 or 1, o=0-3, p=0-3, and the summ+n+p=the same as the state of oxidation of the transition metal M.

It is preferable if the metallocene used in the process according to theinvention is titanocene or zirconocene, or a mixture of these,preferably zirconocene. Typical metallocenes usable in the invention arelisted, for example, on pages 10-12 of Finnish patent application No.862525, which is incorporated herein by reference. Some examples ofusable metallocenes are biscyclopentadienylzirconium dichloride Cp₂ZrCl₂and bisindenylzirconium dichloride Ind₂ZrCl₂.

The alumoxanes used in the process form with the metallocene an activeion pair, i.e. they generate a positive charge in the transition metal.They thus ionize a neutral metallocene compound to a cationicmetallocene catalyst, as stated, for example, in U.S. Pat. No.5,242,876. Alumoxane compounds are comoosed of oligomeric linear and/orcyclic hydrocarbyl alumoxanes. According to one embodiment of theinvention, the alumoxane is a linear compound according to Formula (II).

or a cyclic compound according to Formula (III)

in which formulae x is 1-40, preferably 10-20, y is 3-40, preferably3-20, and R″ is an alkyl group having 1-10 carbon atoms, or a mixture ofthe compounds of formulae (II) and (III).

Alumoxanes can be prepared, for example, by contacting water or ahydrogenated inorganic salt with aluminum trialkyl, whereby in general amixture of linear and cyclic compounds is obtained. An alumoxaneespecially advantageous for use in the process according to the presentinvention is methylalumoxane, MAO, i.e. a compound according to Formula(II) and/or (III), where R″ is methyl.

The support used in the process according to the invention may be anyporous, subtantially inert support, such as an inorganic powder, e.g. aninorganic oxide or salt. In practice the support used is preferably afine-grained inorganic oxide such as an inorganic oxide of an element ofgroup 2(A), 3(B) or 4 of the Periodic Table (Hubbard), most preferablysilica, alumina, or a mixture or derivative of these. Other inorganicoxides which can be used either alone or together with silica, aluminaor silica-alumina, are magnesium oxide, titanium dioxide, zirconiumoxide, aluminum phosphate, etc.

The support used in the process according to the invention should bedry. In gneral, metal oxide supports also contain surface hydroxylgroups which may react with metallocene or alumoxane. Before being used,an inorganic oxidic support may be dihydrated and possiblydehydroxylated. Such treatment may be either a thermal treatment or areaction between the surface hydroxyls of the support and a reagentcontacted with it.

Thermal treatment of the support is in general carried out either undervacuum or by rinsing with a dry inert gas at approx. 100-800° C.,preferably 200-600° C. The support may also be subjected to a chemicaltreatment in which the surface hydroxyls are caused to react withsubstances reacting with them. Such chemical dehydroxylation reagentsinclude SiCl₄, chlorosilanes such as trimethylchlorosilane, otherreactive silanes such as dimethylaminotrimethyl silane orhexamethyldisilazane, alkyl amines, and alkylaluminum chlorides such astriethylaluminum, diethylaluminum chloride, etc.

The present invntion is based on the idea that the metallocene andalumoxane are first caused to react with each other, and a solution isprepared from their reaction product. A solid support is thenimpregnated with the solution, which is adsorbed to all pores andcrevices of the support, their surfaces becoming therby activated. By aporous support is meant in this context a support which adsorbs moreliquid than an entirely smooth-surfaced support. In practice thequestion is not necessarilly of a support in which a substantial portionof the particle volume is pore volume; it suffices that the support isin general capable of adsobing liquid. It is, however, preferable to usea support having a pore volume of approx. 0.9-3.5 ml/g. This purpose ofthe invention is also evident from the description presented at thebeginning of the present application.

The solvent used in step (3) of the process according to the inventionis any solvent which is capable of bringing a metallocene and alumoxanetogether and to dissolve the reaction product formed by them. Typicalsolvents include various oils of mineral origin and hydrocarbons such aslinear and cyclic alkanes and aromatics. Especially preferred solventsinclude aromatics, e.g. toluene. An expert in the art is capable byexperimentation to determine the optimal solvent quantity with which thetransition-metal concentration in the support, calculated as zirconium,will be the above-mentioned 0.2-2.0% by weight, preferably 0.6-1.6% byweight.

In step (2) of the process according to the invention, a solution isprovided which comprises the reaction product of a metallocene and analumoxane and a solvent. Thereafter the reaction product, the solventand a porous support are brought into contact. The solution formed bythe raction product and the solvent may be prepared either by ractingthe metallocene and the alumoxane and by dissolving the abtainedreaction product in the solvent, or by bringing together separatesolutions and/or slurries of the metallocene and the alumoxane, or byadding the metallocene and the alumoxane to the same solvent, whereuponthe react with each other. The components may be brought together or beadded to the reaction mixture rapidly or slowly. The reactingtemperature of the metallocene and the alumaxane, or the preparationtemperature of the solution, may vary widely, for example within therange 0-100° C. preferable temperature is aproximately room temperature.The reaction period may vary greatly within the range approx. 30 min-20h, but it is preferable to maintain the reaction for approximately onehour. Since the metallocene and the alumoxane are in general highlysensitive to the oxygen and moisture of air, they must be shielded forthe duration of the reaction and the preparation of the solution with anatmosphere of an inert cas such as nitrogen. The obtained reactionproduct of the metallocene and alumoxane, or its solution, must also bestored in an oxygen-free and dry space.

The catalyst may be prepared in any reaction vessel, as long as it isprovided with sufficiently good stirring, in order that the componentscan be distributed evenly within the support. Preferred reactor typesinclude a so-called pivotable multi-purpose reactor, in which theposition of the reactor can be changed, or a conventional batch reactorequipped with sufficient stirrer means.

In addition to the process described, the invention also relates to asupported olefin polymerization catalyst prepared by the process. Sincethe chemical composition and physical structure of such a catalyst arevery difficult to describe, the describing is best done by defining thecatalyst by its preparation process, described above. On the basis ofthe above specification it can, however, be stated that a supportedolefin polymerization catalyst according to the invention differs fromprior corresponding supported catalysts based on a metallocene and anactivator in that the pores of the support are more completely and moreevenly filled with the catalytically active reaction product of themetallocene and the alumoxane.

In any case it is clear that, if the components have been contacted withthe support separately, or if the support has been immersed in asolution of the reaction product, the reaction between the metalloceneand the alumoxane has not been the same in the different parts of thecatalyst particles. it is evident that the reactions in the outer partsof a catalyst particle are different from those in its inner parts. Suchlayered quality of the catalyst particles can excellently be detected bythe SEM-EDS method, in which metal concentrations are measured fromcross-sectioned catalyst particles.

In addition to said catalyst and the process for its preparation, theinvention also relates to the use of the catalyst for the homo- andcopolymerization of olefins, preferably of ethylene and/or propylene.The comonomers used may be C₂-C₂₀ olefins, dienes or cyclic olefins orthe like.

One of the best properties of the present catalysts is their ability toproduce polyethylene having a high bulk density. According to apreferred embodiment of the invention, ethylene is slurry polymerizedusing a supported olefin polymerization catalyst prepared by

(1) providing a porous support, which is an inorganic oxide of anelement chosen from groups 2(A), 3(B) and 4 of the Periodic Table(Hubbard),

(2) providing a solution comprising

(2.1) the reaction product of

(2.1.1) a metallocene of the formula (I)

(Cp)_(m)R_(n)MR′_(o)X_(p)  (I)

 wherein Cp is an unsubstituted or substituted and/or fused homo- orheterocyclopentadienyl, R is a group of 1-4 atoms connecting two Cprings, M is a transition metal of group 4A, 5A or 6A, R′ is ahydrocarbyl or hydrocarboxy group having 1-20 carbon atoms, and X is ahalogen atom, in which case m=1-3, n=0 or 1, o=0-3, p=0-3, and the summ+n+p=the same as the state of oxidation of M, and

(2.1.2) an alumoxane of the formula (II)

R″—(AlO)_(x)—AlR″₂  (II)

 which formula (II) depicts a linear compound, and/or of the formula(III)

 which formula (III) dipicts a cyclic compound, and in which formulae(II and III) x is 1-40, preferably 10-20, y is 3-40, preferably 3-20,and R″ is an alkyl group having 1-20 carbon atoms, and

(2.2) a solvent, capable of dissolving said reaction product,

(3) impregnation the porous support with a volume of the solution, whichdoes not exceed the total pore volume of the porous support, and

(4) recovering the impregnated porous support, the pores of which arefilled with said solution.

By such a process, a polyethylene bulk density of up to three times thedensity of conventional slurry polymerized polyethylene, is obtained.Compare examples 2-5 according to the invention with examples 1 and 6according to conventional technique. In the process according to theinvention, polyethylene having a bulk desity of at least 280 kg/m³,preferably about 300 kg/m³, is prepared.

The slurry polymerization of ethylene is preferably carried out in ahydrocarbon medium, most preferably in pentane.

A number of embodiment examples are presented below, their only purposebeing to illustrate the invention.

EXAMPLE 1 Cyclopentadienylzirconium Chloride/MAO Slurry

Preparation of the Catalyst:

A solution was prepared which contained 11.07 ml of a 10 wt. % MAOsolution in toluene, to which 0.138 g of Cp₂ZrCl₂ had been added. Thesolution was mixed until the cyclopentadiene-zirconium compound haddissolved. To the complex solution was added 3 g of GRCACE 955 W silicawhich had a pore volume of 1.5-1.7 ml/g and which had been calcined at600° C. for 10 h for the removal of water and surface hydroxyls. Themixture was allowed to mix for 8 h, whereafter the toluene wasevaporated off.

Polymerization of the Catalyst:

The catalyst was polymerized in a 70° C. pentane slurry. The partialpressure of ethylene was 10 bar and the hydrogen amount used was 175ml/l bar H₂. The catalyst amount used in the test polymerization was 277mg. After one hour, the polymerization was discontinued by closing thereed of ethylene and by starting the cooling of the reactor. The yieldof the reaction was 50 g of polyethylene, which gives 360 g PE/g cat has the activity of the catalyst.

Analyses of the Polymer:

The bulk density of the polymer was 100 kg/m², MFR₂=16, MFR₅=60,MFR_(5/2)=3.

EXAMPLE 2 Cyclopentadienylzirconium Chloride/MAO Dry Mixing Preparationof the Catalyst:

1 g of GRACE 955W silica calcined at 500° C. is placed in a glass flaskhaving an inert atmosphere, for example dry and oxygen-free argon ornitrogen. 1.5 ml of a freshly prepared Cp_(n)ZrCr₂/MAO complex solutionis added in drops onto the silica so that the Zr concentration on thesupport will be 1% by weight and Al/Zr=50. Thereafter, the excesstoluene is evaporated by using nitrogen blowing.

Polymerization of the Catalyst:

The catalyst was polymerized at 70° C. in a pentane slurry. The partialpressure of ethylene was 10 bar and the hydrogen amount used was 1550ml/1 bar H₂. The catalyst amount used in the test polymerization was 73mg. After one hour, the polymerization was discontinued by closing thefeed of ethylene and by starting the cooling of the reactor. The yieldof the reaction was 22 g of polyehylene, which gives 300 g PE/g cat h asthe acivity of the catalyst.

Analyses of the polymer:

The bulk density o f the polymer was 300 kg/m³, Mw=5500 g mol⁻¹,polydispersity 3.1, MFR₂=>300, FRR_(21/2)=not measurable. As can beobserved from this example, the bulk density (BD) of the polymer hasincreased considerably as compared with the slurry preparation processdescribed in Example 1.

EXAMPLE 3 Bisindenylzirconium Chloride/MAO Dry Mixing Preparation of theCatalyst:

1 g of GRACE 955W silica calcined at 500° C. is placed in a glass flaskhaving an inert atmosphere, for example dry and oxygen-free argon ornitrogen. 1.5 ml of a freshly prepared Ind₂ZrCl₂/MAO complex solution isadded in drops onto the silica so that the Zr concentration on thesupport will be 1% by weight and Al/Zr=50. Thereafter, the excesstoluene is evaporated by using nitrogen blowing.

Polymerization of the Catalyst:

The catalyst was polymerized at 70° C. in a pentane slurry. The partialpressure of ethylene was 10 bar and the hydrogen amount used was 1550ml/1 bar H₂. The catalyst amount used in the test polymerization was 85mg. After one hour, the polymerization was discontinued by closing thefeed of ethylene and by starting the cooling of the reactor. The yieldof the reaction was 378 g of polyethylene, which gives 4100 g PE/g cat has the activity of the catalyst.

Analyses of the Polymer:

The bulk density of the polymer was 280 kg/m³, Mw=192,000 g mol⁻¹polydispersity 8.4, MFR₂₁=8.0, MFR₂=0.3, FRR_(21/2)=26.7.

EXAMPLE 4 Bisindenylzirconium chloride/MAO Dry Mixing (large batch)

Preparation of the Catalyst:

1000 g of GRACE 955 silica calcined at 500 for the removal of excess OHgroups is placed in a catalyst synthesis reactor. 1500 ml of a freshlyprepared Ind₂ZrCr₂/MAO complex solution is added in drops onto thesilica so that the Zr concentration of the catalyst will be 1% by weightand Al/Zr=50. When all of the complex has been added onto the support,the evaporation of toluene is started immediately at room temperature,by using nitrogen blowing.

Polymerization of the Catalyst:

The catalyst was polymerized at 70° C. in a pentane slurry. The partialpressure of ethylene was 10 bar and the amount of hydrogen used was 1550ml/1 bar H₂. The catalyst amount used in the test polymerization was 71mg. After one hour, the polymerization was discontinued by closing thefeed of ethylene and by starting the cooling of the reactor. Thecatalyst amount was 71 mg and the yield was 468 g of polyethylene, whichgives 6600 g PE/g cat h as the activity of the catalyst.

Analyses of the Polymer:

The bulk density of the polymer was 300 kg/m³, MFR₂=0.2, MFR₂₁=3.6.

EXAMPLE 5 Cyclopentadienylzirconium chloride/MAO Pore Filling (largebatch)

Preparation of the Catalyst:

1090 g of GRACE 955 silica (P.V.=1.5-1.7 ml/g) calcined at 600° C. forthe removal of excess OH groups is placed in a catalyst synthesisreactor. 1.5 l of a freshly prepared Cp₂ZrCl₂/MAO complex solution isadded in drops onto the silica so that the Zr concentration of thecatalyst will be 1% by weight and Al/Zr=25. When all of the complex hasbeen added onto the support, the evaporation of toluene is startedimmediately at room temperature by using nitrogen blowing.

Polymerization of the Catalyst:

The catalyst was polymerized at 70° C. in a pentane slurry. The partialpressure of ethylene was 10 bar and the hydrogen amount used was 105ml/1 bar H. The amount of catalyst used in the test polymerization was296 mg. After one hour, the polymerization was discontinued by closingthe feed of ethylene and by starting the cooling of the reactor. Theyield of the reaction was 79 g of polyethylene, which gives 270 g PE/gcat h as the activity of the catalyst.

Analyses of the Polymer:

The bulk density of the polymer was 280 kg/m³ MFR₅=89.7, MFR₂=33.0,MFR_(5/2)2.7.

EXAMPLE 6 Cyclopentadienylzirconium Chloride/MAO Slurry (large batch)

Preparation of the Catalyst:

1000 g of GRACE 955 W silica (P.V.=1.5-1.7 ml/g) calcined at 600° C. wasplaced in a catalyst synthesis reactor. 3750 ml of a 10 wt. % MAOsolution in toluene was added onto the silica. The mixture was stirredovernight, whereafter the toluene was evaporated. When the product wasdry, onto it was added 1450 ml of a toluene solution to which 13 g ofCp₂ZrCl₂ had been added. Thereafter the excess toluene was evaporated,whereafter the catalyst was ready.

Polymerization of the Catalyst:

The catalyst was polymerized at 70° C. in a pentane slurry. The partialpressure of ethylene was 10 bar, and the hydrogen amount used was 175ml/1 bar H₂. The catalyst amount used in the test polymerization was 222mg. After 1 h 52 m mn the polymerization was discontinued by closing thefeed of ethylene and by starting the cooling of the reactor. The yieldof the reaction was 110 g of polyethylene, which gives 247 g PE/g cat has the activity of the catalyst.

Analyses of the Polymer:

The bulk density of the polymer was 100 kg/m³. A comparison of the bulkdensity of tnis example to the bulk density of the previous exampleshows again that the morphology of a polymer prepared by a slurryprocess is poor.

EXAMPLE 7 Fluidized Bed Gas Phase Pilot Plant Test, Dry Mixed Catalyst

Catalyst Preparation: See Example 5.

Polymerization of the Catalyst:

Catalyst prepared according to patent example 5 was tested in fluidizedbed gas phase reactor. Reactor temperature was 80° C., ethylene artialpressure was 13 bar and production rate was 10 kgPE/h.

Analyses of the Polymer:

MFR₂₁=15.8, MFR₂=0.52, FPR_(21/2)=29.2, Density=0.9545, Ash content 940ppm, Bulk density 530 kg/m³. Polymer particle distribution: see FIG. 1.Polymer Mw versus particle size: see FIG. 2. Polydispersity versusparticle size: see FIG. 3.

EXAMPLE 8 Fluidized Bed Gas Phase Pilot Plant Test, Slurry PreparedCatalyst

Catalyst Preparation: See Example 6.

Polymerization of the Catalyst:

Catalyst prepared according to patent example 6 was tested in fluidizedbed gas phase reactor. Reactor temperature was 80° C., ethylene partialpressure was 11 bar and production rate was 3-7 kgPE/h.

Analyses of the Polymer:

MFR₂₁=300-900, MFR₂=2-7, FRR_(21/2)=150, Density=0.963, Ash content 185ppm, Bulk density 530 kg/m³. Polymer particle distribution: see FIG. 4.Polymer Mw versus particle size: see FIG. 5. Polydispersity versusparticle size: see FIG. 6.

COMPARATIVE EXAMPLE 9 Slurry Preparation

Preparation of the Catalyst:

Onto 1 g of GRACE 955 W silica (P.V.=1.5-1.7 mL/g), calcinated at 800°C. 10 h for the removal of excess of —OH groups, is mixed 3.4 mL of 10%by weight MAO/toluene solution. This mixture is stirred at 650° C. for 1hour. Then a mixture of metallocene (bis(n-butylcyclopentadienyl)ZrCl₂)and toluene is added to the reactor and allowed to react 30 minutes at65° C. The catalyst is then dried under nitrogen.

Analyses of the Catalyst:

SEM (Scanning Electron Microscope) pictures of catalyst particles areshowing inhomogeneous particle structure with lot of catalyst fines.Also single catalyst particles seem to have some kind of crystals ontoparticle surface. These crystals are evidently crystallisedMAO/metallocene structures.

Polymerization of the Catalyst:

Catalyst was polymerized in a 3L autoclave at 700° C. pentane slurry.The partial pressure of ethylene was 10 bar and the hydrogen amount was1550 mL/1 bar H₂. The catalyst amount used in test polymerization was 76mg. After 60 min polymerization the polymerization was stopped byclosing the feed of ethylene and by starting the cooling of the reactor.The yield of the reaction was 323 g of polyethylene which gives 4250 gPE/g cat h as the activity of the catalyst.

Analyses of the Polymer

The bulk density of the polymer was 147 kg/m³, MFR₂=2.73, MFR₂₁=76.5.Sieving of the polymer: see FIG. 7.

SEM pictures were also taken from polymer formed with catalyst used. Theinhomogeneity of polymer is seen very clearly. Polymer particlestructure is very porous and particle morphology is very bad.

EXAMPLE 10 Pore filling Method

Preparation of the Catalyst:

1143 g or GRACE 955 W silica (P.V.=1.5-1.7 mL/g), calcinated at 500° C.for the removal of excess of —OH groups, is placed in a catalystsynthesis reactor. 1700 mL of a freshly preparedn-butylcyclopentadienyl-ZrCl₂/MAO/toluene complex solution is added indrops onto the silica, so that the Zr content of the catalyst will be0.25% by weight and Al/Zr=200. When all of the complex has been addedonto the support, the evaporation of toluene is started immediately atroom temperature.

Analyses of the Catalyst:

SEM (Scanning Electron Microscope) pictures of catalyst particles areshowing very homogenous catalyst structure without any fines orcrystalline structures onto catalyst surface.

Polymerization of the Catalyst:

Catalyst was polymerized in a 3L autoclave at 80° C. pentane slurry. Thepartial pressure of ethylene was 10 bar and the hydrogen amount was 1550mL/1 bar H₂. The catalyst amount used in test polymerization was 74 mg.After 60 min polymerization the polymerization was stopped by closingthe feed of ethylene and by starting the cooling of the reactor. Theyield of the reaction was 205 g of polyethylene which gives 2800 g PE/gcat h as the aczivity oL the catalyst.

Analyses of the Polymer

MFR₂=2.8, MFR₂₁=76.5. Sieving of the polymer: see FIG. 8.

SEM pictures were also taken from polymer formed with catalyst used. Thehomogeneity of polymer is seen very easily. Polymer paricle morphologyis excellent and catalyst particle replica phenomena has worked well.

EXAMPLE 1 Pore Filling Method

Preparation of the Catalyst:

940 g of GRACE 955 W silica (P.V.=1.5-1.7 mL/g), calcsinated at 600° C.for the removal of excess of —OH groups, is placed in a catalystsynthesis reactor. 1400 mL of a freshly preparedbisindenyl-ZrCl₂/MAO/toluene complex solution is added in drops onto thesilica, so that the Zr content of the catalyst will be 1% by weight andAl/Zr=50. When all of the complex has been added onto the support, theevaporation of toluene is started immediately at room temperature.

Analyses of the Catalyst:

SEM (Scanning Electron Microscope) pictures of catalyst particles areshowing very homogeneous catalyst structure without any fines orcrystalline structures onto catalyst surface.

Polymerization of the Catalyst:

Catalyst was polymerized in a 3L autoclave at 70° C. pentane slurry. Thepartial pressure of ethylene was 10 bar and the hydrogen amount was 1550mL/1 bar H₂. The catalyst amount used in test polymerization was 70 mg.After 60 min polymerization the polymerization was stopped by closingthe feed of ethylene and by starting the cooling of the reactor. Theyield of the reaction was 302 g of polyethylene which gives 4300 g PE/gcat h as the activity of the catalyst.

Analyses of the Polymer

Bulk Density=250 kg/m³, MFR₂=0.23, MFR₂₁=4.9. Sieving of the polymer:see FIG. 9.

SEM pictures were also taken from polymer formed with catalyst used. Thehomogeneity of polymer is seen very easily. Polymer particle morphologyis excellent and catalyst particle replica phenomena has worked well.

TABLE 1 Polymerization catalyst and product characteristics in examples.Pore Total Used Activity g volume/ pore liquid Polymerization kgPE/g Exsupport ml/g volume e volume e medium cat h MFR₂ MFR₂₁ BD/mg/m³ LigandL¹⁾ 1 3 1.5-1.7 4.5-5.1 11.07 Pentane Slurry 0.36 16 Very high 100 Cp 21 1.5-1.7 1.5-1.7 1.5 Pentane Slurry 0.30 300 Very high 300 Cp 3 11.5-1.7 1.5-1.7 1.5 Pentane Slurry 4.10 0.3  8.0 280 Ind 4 1000 1.5-1.71500-1700 1500 Pentane Slurry 6.6 0.2  3.6 300 Ind 5 1090 1.5-1.71500-1700 1500 Pentane Slurry 0.27 33 Very high 280 Cp 7 1090 1.5-1.71500-1700 1500 Gas Phase Pilot −1.0 0.52 15.8 530 Cp 6 1000 1.5-1.71500-1700 3750 Pentane Slurry 0.25 100 Cp 8 1000 1.5-1.7 1500-1700 3750Gas Phase Pilot −0.5 2-7 300-900 530 (but material Cp inhomogeneous 9 11.5-1.7 1.5-1.7 3.4 Pentane Slurry 4.3 2.73 76.5 147 n-BuC_(p) 10 11431.5-1.7 1715-1943 1700 Pentane Slurry 2.8 2.8 76.5 250 n-BuC_(p) 11 9401.5-1.7 1190-1598 1400 Pentane Slurry 4.3 0.23  4.9 250 Ind ¹⁾C_(p) =cyclopentadienyl Ind = indenyl n-Buc_(p) = n-butyl cyclopentadienyl

What is claimed is:
 1. A process for the preparation of ethylenecopolymers consisting essentially of: (1) providing a porous support,which is an inorganic oxide of an element selected from the groupconsisting of Groups 2(A), 3(B), and 4 of the Periodic Table (Hubbard);(2) providing a solution consisting essentially of (2.1) a reactionproduct of (2.1.1) a metallocene of the formula (I)(Cp)_(m)R_(n)MR′_(o)X_(p)  (I)  wherein Cp is an unsubstituted orsubstituted and/or fused cyclopentadienyl group, R is a group of 1-4atoms connecting two Cp rings, M is a transition metal selected from thegroup consisting of Groups 4A, 5A and 6A, R′ is a hydrocarbyl orhydrocarboxy group having 1-20 carbon atoms, and X is a halogen atom,wherein m=2-3, n=0 or 1, o=0-3, p=0-3, and the sum m+o+p=the same as thestate of oxidation of M, with (2.1.2) an alumoxane of the formula (II)

 which formula (II) depicts a linear compound, and/or of the formula(III)

 which formula (III) depicts a cyclic compound, and in which formulae(II and III) x is 1-40, y is 3-40, and R″ is an alkyl group having 1-20carbon atoms, and (2.2) a solvent, capable of dissolving said reactionproduct; (3) impregnating said porous support with a volume of thesolution, which does not exceed the total pore volume of the poroussupport; and (4) recovering the impregnation product as a supportedethylene co-polymerization catalyst; and (5) conducting a slurryco-polymerization of ethylene in a hydrocarbon medium and in thepresence of essentially only said supported ethylene co-polymerizationcatalyst.
 2. The process according to claim 1, comprising impregnatingsaid porous support with an amount of said solution equal to its porevolume.
 3. The process according to claim 1, wherein the molar ratio ofthe alumoxane to the metallocene, calculated as the ratio of aluminum tothe transition metal, is within the range 50:1-25:1.
 4. The processaccording to claim 1, wherein the metallocene is selected from the groupconsisting of a titanocene and a zirconocene, or a mixture thereof. 5.The process according to claim 1, wherein the alumoxane ismethylalumoxane.
 6. The process according to claim 1, wherein the poroussupport is selected from the group consisting of a silica and analumina, or a mixture or derivative thereof.
 7. The process according toclaim 6, wherein the porous support has been treated thermally and/orchemically for the removal of water and any surface hydroxyls.
 8. Theprocess according to claim 1, wherein the solvent is a hydrocarbon. 9.The process according to claim 1, wherein x in formula II is 10-20. 10.A process for the preparation of ethylene copolymers consistingessentially of: (1) providing a porous support, which is an inorganicoxide of an element selected from the group consisting of Groups 2(A),3(B), and 4 of the Periodic Table (Hubbard); (2) providing a solutionconsisting of (2.1) a reaction product of (2.1.1) a metallocene of theformula (I) (Cp)_(m)R_(n)MR′_(o)X_(p)  (I)  wherein Cp is anunsubstituted or substituted and/or fused cyclopentadienyl group, R is agroup of 1-4 atoms connecting two Cp rings, M is a transition metalselected from the group consisting of Groups 4A, 5A and 6A, R′ is ahydrocarbyl or hydrocarboxy group having 1-20 carbon atoms, and X is ahalogen atom, wherein m=2-3, n=0 or 1, o=0-3, p=0-3, and the summ+o+p=the same as the state of oxidation of M, with (2.1.2) an alumoxaneof the formula (II)

 which formula (II) depicts a linear compound, and/or of the formula(III)

 which formula (III) depicts a cyclic compound, and in which formulae(II and III) x is 1-40, y is 3-40, and R″ is an alkyl group having 1-20carbon atoms, and (2.2) a solvent, capable of dissolving said reactionproduct; (3) impregnating said porous support with a volume of thesolution, which does not exceed the total pore volume of the poroussupport; and (4) recovering the impregnation product as a supportedethylene co-polymerization catalyst; and (5) conducting a slurryco-polymerization of ethylene in a hydrocarbon medium and in thepresence of essentially only said supported ethylene co-polymerizationcatalyst.